Construction of a New Dipole Trap for Non-neutral Plasma

A magnetic dipole has the necessary symmetry to take advantage of canonical angular momentum conservation for confining non-neutral plasma. Recent theory and computation identified stable global thermal equilibrium states (Steinbrunner 2023). Such states require tailored electrostatic boundary conditions and are localized to the equatorial region; they are therefore likely to be accessible in a trap with a supported magnet. A trap has been constructed at Lawrence University to confirm whether these states can be produced experimentally. In the Lawrence Non-neutral Dipole (LND) device, a neodymium magnet (3” diameter disk with a surface magnetic field of 2.3 kG on axis) is mounted on a central support and can be biased relative to the vacuum chamber as theory demands. We employ a LaB6 emitter to inject electrons from the equator and use multiple copper wall probes to monitor image charge signals.

This material is based upon work supported by the National Science Foundation under Grant No. 2206620.

P. Steinbrunner, T. M. O’Neil, M. R. Stoneking, and D. H. E Dubin, J. Plasma Phys. 89, 935890401 (2023).